Small plastic particles are omnipresent in our environment, posing a potential threat to species, but the difficulty is knowing how best to measure concentrations. Ecotoxicologist Dr Richard Cross explains how an innovation by the UK Centre for Ecology & Hydrology can support this vital monitoring worldwide...
Microplastics have been found across the world, from the bottom of oceans, to the tops of mountains.
Not only are they entering our environment, but they are also making their way into wildlife, with over 1,500 different species now observed to have ingested microplastics. But sometimes, it’s tricky to get your head around the numbers.
As this is a relatively new area of research, scientists as a community are exploring different ways to measure and quantify microplastics out there, in nature. We like to think of microplastics as a single ‘thing’, but actually, the word encompasses a whole range of sizes, shapes and polymers (that’s the chemical identity of the material, with which you’ll be familiar from the different labels on recyclable plastics).
No single analytical instrument can measure this whole diversity of microplastics. As plastics degrade and disintegrate in the environment, they become more and more numerous. This means, for example, that microscopes capable of measuring smaller microplastics will count more particles than those that can only measure larger microplastics.
Common method
In order to make sense of this, we need to agree common ways that researchers, environmental managers and regulators can interpret observations of microplastics, which can be measured using any number of different techniques in laboratories across the world.
Usually when we go out into ‘the field’ to measure microplastics, we are taking only a small portion of the environment we want to study and bringing it back to the lab for analysis. You can’t collect the whole of the Thames to find out how many microplastics there are in it!
But how do we know we took enough water from the river to be sure that we can detect microplastics reliably? This is why scientists at the UK Centre for Ecology & Hydrology (UKCEH) have developed a new statistical tool by the name of RSVP – the Representative Sample Volume Predictor.
Now, no matter what you are using to measure microplastics in the lab, we can all follow the same procedure to check that we have taken a representative sample – one that reflects the environment we are trying to understand.
Identifying risks
It is important that we continue to monitor the presence of microplastics in the environment in order to identify where they are coming from, what risks they pose and how we might reduce these risks in the future.
Having common, transparent methods that can be used, no matter where you are working in the world, will help us harmonise and interpret the data on microplastics that we are generating day in, day out, all across the planet.
The tool is a downloadable spreadsheet accompanying a paper explaining our methods in the journal Microplastics and Nanoplastics. It provides calculations to predict how much water you should take from a river, sea or ocean to capture microplastic particles with a given level of confidence.
UKCEH has made this tool freely available to the research community, so people can test, use and report on the plastic particles present in the natural world in a consistent way. So, to borrow a phrase, if you are measuring microplastics out there in the wild, always remember to RSVP!
Further information
The spreadsheet tool is available in the supplementary information section of the paper: Cross et al. 2025. Ensuring representative sample volume predictions in microplastic monitoring. Microplastics and Nanoplastics. DOI: 10.1186/s43591-024-00109-2
The work was part-funded by Exxon Mobil Biomedical Sciences Ltd. with additional support from UK Research and Innovation under the UK Government’s Horizon Europe funding guarantee, as part of the UPSTREAM project.
